An island detection method and an island detection system

An island detection and coordinate system technology, which is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables, can solve the problems of affecting the quality of inverter output power and large blind areas of island detection, and achieve the elimination of island detection blind areas and steady-state power Good quality and wide range of effects

Active Publication Date: 2021-07-09
HEFEI WIN POWER
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Problems solved by technology

[0005] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide an islanding detection method and an islanding detection system, which are used to solve the problems in the prior art that the blind area of ​​the islanding detection is large and the quality of the inverter output power is affected by the amount of disturbance injected. question

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  • An island detection method and an island detection system
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  • An island detection method and an island detection system

Examples

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Embodiment 1

[0042] The invention provides an islanding detection method, which is suitable for a grid-connected inverter that adopts grid voltage orientation, and the grid-connected inverter has a local load, and the local load can be pure resistive load, inductive load and capacitive load. random combination.

[0043] see figure 1 , is a grid-connected inverter topology with local load (RLC), point A is the grid-connected point, and its power equation can be described as:

[0044] P load +jQ load =(P inv +ΔP)+j(Q inv +ΔQ)

[0045] Among them, P load Active power dissipated for the local load, Q load Reactive power dissipated for local load, P inv is the active power output by the grid-connected inverter, Q inv is the reactive power output by the grid-connected inverter, ΔP is the active power exchanged between the grid-connected point and the grid, and ΔQ is the reactive power exchanged between the grid-connected point and the grid. When it is zero, that is, the grid-connected in...

Embodiment 2

[0072] see Figure 7 , the present application also discloses an islanding detection system, the system includes: a sampling module (not shown) for sampling three-phase voltage and three-phase current signals of the grid-connected point; a phase-locked loop 1 for The three-phase voltage signal U of the network point a , U b , U c Phase locking is performed, and the angle orientation error value err_q of the voltage at the grid-connected point is output; the proportional-differential regulator 2 is used to perform proportional-differential adjustment on the angle orientation error value err_q to obtain the disturbance amount of the reactive power command of the grid-connected inverter ΔVq; the adder 3 is used to superimpose the disturbance quantity ΔVq of the reactive power command on the grid-connected inverter reactive current command Iq_ref; the reactive power control module 4 is used to superimpose the reactive power according to the superimposed disturbance quantity The...

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Abstract

The invention provides an island detection method, which superimposes the orientation error of the grid voltage phase angle as a positive feedback of the disturbance on the reactive current command, thereby adjusting the reactive power output of the grid-connected inverter. When the grid contactor is disconnected When the islanding effect occurs, the frequency deviation of the grid-connected point voltage leads to the generation of orientation angle errors. Further, the reactive current command performs positive feedback adjustment, which increases the frequency deviation of the grid-connected point voltage, and finally exceeds the threshold, triggering detection The system is passively protected and shut down successfully. The islanding detection method and the islanding detection system of the present invention eliminate the blind area of ​​the islanding detection, are simple to control, and can quickly and accurately detect the islanding of the inverter; meanwhile, the power quality is not affected during grid-connected operation.

Description

technical field [0001] The invention relates to the technical field of grid-connected power generation, in particular to an island detection method and an island detection system. Background technique [0002] As an energy exchange device between renewable energy and the power grid, grid-connected inverters have been widely used in new energy power generation systems including wind power generation, photovoltaic power generation, and wave power generation. Distributed power generation systems are usually composed of new energy power generation devices, local loads and distribution networks. The grid-connected inverters and the power grid jointly supply power to the loads. [0003] When the grid is disconnected from the inverter due to faults or line disconnection, the grid-connected inverter is connected to the load, and the grid-connected point loses the support of voltage and frequency. The voltage amplitude and frequency of the grid-connected point are determined by the c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/00G01R19/00
CPCG01R19/00G01R31/00
Inventor 张为民周一晨庞博
Owner HEFEI WIN POWER
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